TABLE 1.

Alpha richness and diversity of the rhizosphere bacterial communities determined during long-term N application.

Index	Year	N0	N120	N180	N240	N360
Chao	1	34.94 ± 1.74a	32.88 ± 1.55a	36.13 ± 8.93a	32.75 ± 3.93a	31.88 ± 2.29a
	5	32.81 ± 1.57a	31.75 ± 0.96a	31.75 ± 1.32a	31.42 ± 0.79a	35.13 ± 7.98a
	10	35.77 ± 8.76a	32.63 ± 0.92a	31.96 ± 2.16a	30.77 ± 3.70a	30.65 ± 1.17a
Shannon	1	2.01 ± 0.04a	2.08 ± 0.03a	2.08 ± 0.02a	2.02 ± 2.02a	2.01 ± 0.09a
	5	2.03 ± 0.05a	2.06 ± 0.02a	2.04 ± 0.04a	2.08 ± 2.08a	2.01 ± 0.09a
	10	1.96 ± 0.06a	1.96 ± 0.04b	1.96 ± 0.03b	1.93 ± 1.93b	1.96 ± 0.03a

Different lowercase letters after the same column value indicate that the difference between the various treatments under the same crop reached a significant level (P < 0.05). Chao reflects community richness and Shannon reflects community diversity. Five N treatments: N₀ (0 kg N hm^–2), N₁₂₀ (120 kg N hm^–2), N₁₈₀ (180 kg N hm^–2), N₂₄₀ (240 kg N hm^–2), and N₃₆₀ (360 kg N hm^–2).